Not Applicable
Not Applicable
Not Applicable
This invention relates to digital data communications over distance-limited wire media. In particular, this invention relates to an apparatus for extending the propagation distance of digital data signals.
There is a need to provide means to extend the effective distance over which digital data signals are communicated via wire in an outdoor environment. Distances may be greater than be supported by the conventional routers and switches. For example, known implementations of 100 BASE-TX physical layer integrated circuits such as the Broadcom AC104QF (from Broadcom, Inc.) typically handle only up to 150 m (492 ft.) of Category 5 cabling at room temperature for speeds up to 100 MBPS. Moreover, power consumption becomes a serious concern because power must be supplied and distributed by the outdoor network. Alternative schemes such as optical fiber are not cost effective for all applications, particularly over relatively short distances of several hundred meters.
A standard has been adopted for electrical and magnetic isolation of electronic circuitry intended to be operated in a severe outdoor environment. The standard is referenced as IEEE 802.3u, IEEE 802.3ab and ANSI X3.236. The specifications provide for operation in a temperature range between 0 and 70 Celsius. For extended operation between xe2x88x9240 C and +85 C, which is more typical of actual experience in some environments, adoption of this standard would be inadequate for reliable operation. Because Category 5 cabling and installation are less expensive than the fiber optic alternative, it is desirable to be able to go farther than the 100 m (328) feet required by the IEEE standard using a low cost cable extender that is powered from the upstream network cable.
According to the invention, an apparatus is provided for deployment in an outdoor environment for extending the electrical communication distance of digital data signals. The apparatus includes electrical isolation means for various electromagnetic effects and a high speed pulse reshaper and repeater. The isolation means includes low capacitance electric pulse suppression means so that maximum signal distance can be achieved without loss of usable pulse shape and isolation transformers on differential signal pairs that retain magnetization at elevated temperatures so that signals are not blocked. As a further feature, extended logic is included whereby the type of signals can be distinguished for speed and duplex settings, thus allowing the apparatus to be daisy-chained with like apparatus or used between a termination and a line.
A network interface data rate and half/full duplex mode may differ from that of the network. Different devices are capable of different speeds and some are capable of only one speed. The speed and duplex mode of the lowest common denominator must be extended to the network switch port to avoid communications breakdown.
The invention will be better understood upon reference to the following detailed description in connection with the accompanying drawings.